checker/tests/nullness/Issue1847.java

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.function.Function;
import org.checkerframework.checker.nullness.qual.KeyFor;

public class Issue1847 {
  final Map<String, String> map = new HashMap<>();

  public void test() {
    // Should give null error here:
    // :: error: (dereference.of.nullable)
    withLookup((String myVar) -> map.get(myVar).length());
    for (Iterator<Map.Entry<@KeyFor("map") String, String>> iterator = map.entrySet().iterator();
        iterator.hasNext(); ) {
      Map.Entry<@KeyFor("map") String, String> entry = iterator.next();
      // Problem is that myVar gets inferred as @KeyFor("map") here,
      // and this variable is not distinguished from the lambda variables of the same name,
      // even though their scopes do not overlap and they are different variables.
      // Change this variable name to myVar2 and you will see the null errors on the lambdas:
      String myVar = entry.getKey();
    }

    // Should also give null error here:
    // :: error: (dereference.of.nullable)
    withLookup(myVar -> map.get(myVar).length());
  }

  public void withLookup(Function<String, Integer> getFromMap) {}
}